Location of underground utility lines

ABSTRACT

Location of underground utility lines, such as telephone cables, gas mains, sewerlines, water mains and electric service lines buried beneath the surface of the earth, by disposing above said lines and below the surface of the earth a colored, flexible, thin metal foil, particularly in the form of a tape and protected against corrosion, the presence and general location of said metal foil being detectable from above the surface of the earth by electronic or like detecting devices.

United States Patent Inventors Gordon 11. Allen Wheaton, Ill.; Robert C.Hosack; Werner P. Schoening; Luther L. Yaeger, all of Houston, Tex.Appl. No. 790,101 Filed Jan. 9,1969 Patented Jan. 11, 1972 AssigneeGriffolyn Company, Incorporated Houston, Tex.

LOCATION OF UNDERGROUND UTILITY LINES 16 Claims, 4 Drawing Figs.

US. Cl 116/114,

61/721 Int. Cl ..G01d 21/00 Field of Search I 16/1 14,

124, DIG. 33; 61/721, 72.4; 161/84, 198, 89, 213, 218,216,214, 165;156/181 [56] References Cited UNITED STATES PATENTS 2,993,806 7/1961Fisher et al. 161/218 X 3,115,861 12/1963 Allen 116/114 3,282,057ll/1966 Prosser 116/114 UX 3,382,136 5/1968 Bugeletal. 161/165 3,455,7757/1969 Pohl et a1 161/216 Primary Examiner Louis J. CapoziAnorney-Wallenstein, Spangenberg, Hattis & Strampel LOCATION OFUNDERGROUND UTILITY LINES This invention relates to facilitatingdetermining the presence and location of utility lines disposed beneaththe surface of earth soils in order to avoid damaging said lines orelements of construction when subsequently excavating or digging intothe earth.

It has heretofore been known, as disclosed in U.S. Pat. No. 3,l 15,861,to facilitate the location, beneath the surface of earth soils and thelike, of elements of construction or utility lines, such as wires,cables, conduit, sewer pipes and sewer connections, valves and likeelements of construction, by digging a trench or providing an excavationin the earth, placing or locating an element of construction or utilityline therein, then placing thereabove a readily frangible colored bodythe color of which contrasts with the surrounding earth soil, and thenfilling or backfilling said trench or excavation with earth. Theimportant, practical advantages of such procedures are disclosed in saidaforesaid patent, and the principles disclosed and taught therein havegone into widespread use. In U.S. Pat. No. 3,282,057, the employment,specifically, of colored plastic sheets or tapes, such as those made ofpolyethylene, is shown, which is an embodiment of a colored frangiblebody, being adapted to be torn when pulled up, for instance, by amechanical digger or the like in connection with an excavationoperation. In actual commercial operation, said colored sheets or tapeshave been used as the embodiment of said colored frangible bodies.

Although such colored plastic sheets or tapes have been widely andsuccessfully used, in the manner described in the aforesaid patents, tofacilitate the location of elements of construction or utility linesbeneath the surface of earth soils and to avoid accidental destructionand damage which commonly occur when such elements or lines areinadvertently and unknowingly encountered when digging beneath thesurface of the earth, there are, nevertheless, certain shortcomings inthe use of said plastic sheets and tapes which the art has not succeededin satisfactorily overcoming.

A major shortcoming of the use of colored plastic sheets or tapes, inthe manner described, for instance, in U.S. Pat. No. 3,282,057, is thefact that its presence beneath the earth surface cannot be ascertainedby any detecting instruments operated from above the surface of earthand is revealed only in connection with a digging operation. The problemis particularly acute in those instances where the lines or elements ofconstruction are nonmetallic, as in the case of clay, ceramic, concrete,or plastic pipe and conduit, for, in such cases, electronic or likemetal detectors fail to reveal the presence of such lines or elements orconstruction.

Various suggestions have been made to attempt to meet this problem. Oneof such suggestions, for instance has been to mark the plastic sheet ortape electromagnetically so that it would be possible to locate andtrace the buried lines or elements of construction with electronicdetecting devices operating from above the surface of the earth. This,and various other suggestions involving the same or similar concepts,and also involving other approaches, have not proved to be practical andnone of such suggestions, so far as we are aware, has come into any use.

It has also heretofore been known, as shown in British Pat. No. 410,900,to provide underground installations wherein a trench is excavated, aline or element of construction, such as a cable, is placed therein, andthe trench is backfilled, a steel tape or sheet being positioned severalinches above the cable to protect it, said steel tape or sheetfunctioning as an armor whereby damage to the cable is prevented by anydigging or similar operations after the underground installation hasbeen made. Such procedure is unrelated to the objectives of the presentinvention and is ineffective to achieve the results of our invention.

The present invention results in an effective and economical solution tothe problem discussed above. We have found that a frangible, flexiblemetal film, in the form of a sheet or tape, carrying a color to contrastwith the color of the earth soil adjacent the lines or elements ofconstruction so that said colors are readily visually distinguishablefrom each other, and wherein said metal film is protected againstmoisture and oxidation or other deterioration when buried in the earthsoil, can effectively be utilized and its presence and general locationcan readily be determined by means of conventional types of electronicor like metal detection devices operating from the surface of the earth.Thus, before any digging or excavation is preformed, the presence andgeneral location of the metal film sheet or tape and, hence, thepresence and location of the nonmetallic line or element ofconstruction, can be ascertained, and the operator of the digging orexcavation equipment forewarned. Various detectors which can be usedare, for instance, the detector sold under the trade designation P-440Metrotech Pipe and Cable Locator and the 220-A Metrotech Valve BoxLocator, or a standard Dipping Needle. Equipment of such and other typesoperate, above the surface of the earth, on inductive and conductiveprinciples to provide strong signals indicating the presence and generallocation of metallic lines beneath the surface of the earth.

The present invention finds its greatest utility, as has been indicatedabove, in those environments where the lines or elements of constructionwhich may be sought to be located are made of nonmetallic materials.

The present invention may take any of several forms or embodiments,which are illustrated in the accompanying drawings wherein FIG. 1 is asectional view taken through a tape showing one embodiment of theinvention, being greatly enlarged in thickness to facilitateillustration of the invention.

FIG. 2 is a sectional view taken through a tape showing anotherembodiment of the invention being greatly enlarged in thickness tofacilitate illustration of the invention.

FIG. 3 is a plan view of still another embodiment of a tape of thepresent invention, a portion of the top protective film being brokenaway.

- FIG. 4 is a section taken along the line 44 of FIG. 3, looking in thedirection of the arrows, being greatly enlarged for illustrativepurposes.

In the embodiment shown in FIG. 1, a synthetic plastic film l, which maybe made, for instance, of polyethylene or polypropylene or, preferably,polyvinylidene chloride (e.g., SARAN") or a fluorocarbon, having athickness of the order of 0.001 to 0.002 inch, carries a more or lesscontinuous metal coating 2 on opposite sides thereof. The metal coating2 may, for instance, be of aluminum which may be deposited as a thinfilm, of the order of a thickness of 0.00005 to 0.0007 inch, byconventional vacuum deposition techniques. On opposite sides of theresulting film, there is a protective coating or film 3 of a syntheticplastic which, again, may be of polyethylene or polypropylene or, moredesirably, is a polyvinylidene chloride (such as SARAN) or afluorocarbon. The film 3 is advantageously applied by laminating it tothe metal coating by passing the assembly through rollers which aredesirably heated sufficiently high so as to impart to the film thesealing temperature of the particular synthetic plastic film utilized.

As indicated above, the finished metal film product should have a colorwhich contrasts with the color of the earth soil surrounding or adjacentto the buried lines or elements of construction. To this end, the film 3may have a color such as red, green, yellow or other color which wouldcontrast with the earth soil. Alternatively, if the film 3 istransparent, then the color of the metal film itself may serve thepurpose of providing to the finished metal film product a colorcontrasting with that of the earth soil. Other procedures are readilyapparent to provide the required color contrast.

In FIG. 2 a tape is shown in which two metal films 4, each of which mayhave a thickness in the range of about 0.0005 inch, are firmly laminatedto each other through a thin film 5 of a laminating adhesive, forinstance, a catalyzed epoxy cement, and then a synthetic plastic film 6,such as he film 3 of FIG. 1, is laminated on the exposed opposite sidesof the metal surfaces. The provision of a color to the finished metalfilm product, which color is selected to contrast with the earth soil,

3 can be effected in the same manner indicated in connection with theembodiment of FlG. l.

in the foregoing embodiments of the invention, the metal film should bea substantially continuous film and should cover a substantial part ofthe area of the finished tape. Thus, for example, the metal film may beessentially coextensive in area with the area of the synthetic plasticfilm; or, again by way of illustration, the metal film may be of thegeneral order of half the width of the synthetic plastic film and may bepositioned approximately centrally of the width of the synthetic plasticfilm or along one or along both edges of said synthetic plastic film,and substantially continuously along the length of said syntheticplastic film.

The metal films for use in the practice of the present invention may beselected from a number of metals, such as aluminum, copper, nickel andferrous metals and alloys, all that is required being that theirpresence and general location below the earths surface be detectable byelectronic or like detecting devices. The metal film may be providedthrough electrodeposition or vacuum deposition or other techniques, as,for instance, by a printer-coating apparatus such as is shown in U.S.Pat. No. 2,766,721 depending upon the type of finished metal filmproduct desired, or through the use of preformed metal films. Thethickness of such metal films is variable but, in general, it isdesirable to provide for a metal film thickness in the range of about0.0005 to about 0.005 inch, excellent results being obtained with anapproximately 0.001 to 0.002- inch thick film.

ln FIGS. 3 and 4, still another embodiment of our invention is shownwherein a tape 7 ofa colored polyethylene, or other moisture andsoil-resistant synthetic plastic, has on its surface a metal wire 8, forexample, made of copper or nickel or a ferrous alloy, in the form of azigzag arrangement. Laminated to the upper surface of the tape 7 isanother tape 9 of colored polyethylene or other synthetic plastic. Avarient of this embodiment, but distinctly less preferred, is initiallyto coat the metal wire with a protective synthetic plastic or similarmaterial, as by passing the metal wire through a hot melt of suchplastic or material, and then bond said coated wire directly to the tapeby passage through heated rollers.

Still other techniques which produce finished metal film products whichcan be employed for the purposes of the present invention involve, forinstance, dusting iron filings into a loose pattern on a syntheticplastic film of the character disclosed above, and then applying amagnetic force to cause said filings to adhere while being bondedtogether either by laminating thereover a synthetic plastic tape bypassage of the assembly through heated rollers, or by spraying over saidfilings a protective adhesive or bonding material. in this latter case,the further application of a thin film of a moistureand soil-resistantsynthetic plastic over the filings is particularly desirable. Again,finished metal film products useful for the purposes of the presentinvention involve printing or coating a thin layer of an adhesive on asynthetic plastic tape, applying iron filings or filings or fibers ofany other electrically conductive metal onto said adhesive layer,followed by the application of a protective synthetic plastic film oversaid electrically conductive metal.

As previously indicated, it is important that the metal film beprotected against oxidation, moisture and other influences present inthe soil beneath the surface of the earth. Any synthetic plastic coatingmaterial which is flexible and itself resistant to deterioration orbreakdown over prolonged periods of time in the earths soils can be usedas a protective coating for the metal film. Polyethylene has been foundto be very satisfactory but, of course, other synthetic plastics, suchas polyvinyl chlorides, acrylonitriles, and including those referred toabove, can be employed.

As has been pointed out above, where the metal film inherently has acoloration which would contrast with the color of surrounding oradjacent earth soil in which it would be embedded, and a transparentsynthetic plastic coating is provided over the metal film, then theapplication of a separate coloration thereto is not necessary. However,in the usual case, it will be found to be desirable to utilize theprotective synthetic plastic film in colored form. in any event, theterm coloring" is used generically, except as may otherwise specificallybe stated, to encompass the color of the finished metal film productwhere it contrasts with earth soil so as to be readily visuallydistinguishable therefrom.

It will be understood that the finished metal film products of thepresent invention can be imprinted with any desired indicia such as, forinstance, are now commercially used on polyethylene tapes employed inthe manner disclosed pursuant to the teachings of the aforementionedpatents. This can be accomplished in any of several ways including, forinstance, initially imprinting the protective plastic films with theselected indicia prior to laminating them over the metal film.

In use, the metal film products described above, in the form of flexiblesheets or tapes; which are adapted to be wound on reels, are applied inthe same manner and utilizing the principles disclosed in theaforementioned patents. Depending upon the nature of the lines orelements of construction, variable widths of the metal film product canbe used, these generally ranging from about 3 inches in width to a footor more in width. The metal film product may be buried from 4 to 12 ormore inches to several feet beneath the surface of the earth and at anappropriate height above the lines or elements of construction, asdescribed, for instance, in the aforementioned U.S. Patents. After themetal foil product is installed in position overlying the lines orelements of construction and the trench or excavation backfilled, if,for any reason, it is necessary thereafter to dig into the earth, say toreach the lines or elements of construction, their presence and generallocation can first be ascertained very simply by means of known types ofelectronic or like metal detection devices. Then, the digging orexcavation can be begun and the colored metal film product will functionin accordance with the same broad principles disclosed in theaforementioned patents. it may also be noted that, although the presenceand general location of the colored metal film products can be andadvantageously is first ascertained by electronic or like detectiondevices, it is not necessary that this be done because the installationaffords the dual purposes of detectability and also the protectivefunction following the principles of said aforementioned patents whereelectronic detectability is not utilized.

The terms frangible," tearable" and rupturable" are used interchangeablyin the claims to means that the strength of the metal film is such that,in conventional digging into the soil in connection, for instance, withexcavating, laying lines or elements of constructions or cutting intothe earth for any other reasons, by means of mechanical or similardigging or excavating equipment, such as backhoes and trenchers, if themetal film is struck and pulled up by such equipment, the teeth or thelike on such equipment will shear, sever or break the metal film andsaid film will be ripped from the earth and be pulled loose, commonlyfor several feet along its length. The terms lines and element ofconstruction are used herein in the same sense in which they have beenas set forth in the aforementioned U.S. Pat. Nos. 3,1 15,86! and3,282,057 respectively.

We claim:

ll. In a method of facilitating the determination of the presence andthe location of an element of construction disposed beneath the surfaceof the earth which includes the steps of digging a trench in the earth,providing an element of construction therein, placing a frangiblecolored body in said trench and overlying said element of constructionand in which said frangible body has a coloring thereon which contrastswith the color of the surrounding earth soil, the improvement in whichsaid frangible colored body comprises a flexible sheet or tape in theform ofa thin base member carry ing a thin film of a metal on itsopposite surfaces, and a thin film protective coating over said metalwhich is moistureand soilresistant.

2. A method according to claim ll, wherein he base member is a syntheticplastic.

3. A method according to claim 1, wherein the base member is anadhesive.

4. In a method of facilitating the determination of the presence and thelocation of an element of construction disposed beneath the surface ofthe earth which includes the steps of digging a trench in the earth,providing an element of construction therein, placing a frangiblecolored body in said trench and overlying said element of constructionand in which said frangible body has a coloring thereon which contrastswith the color of the surrounding earth soil, the improvement in whichsaid frangible colored body comprises a flexible sheet or tape in theform of a thin base member of a synthetic plastic material which ismoistureand soil-resistant, said base member carrying a metal on itssurface, said metal being covered with a thin film protective coatingwhich is moistureand soil-resistant.

5. ln am method for the installation of a line beneath the surface ofthe earth in which the line is placed within an excavation andsubsequently backfilled and wherein there is included in the backfill ata generally predetermined level adjacent the line an indicating meanscomprising a tearable or rupturable flexible sheet or tape bearing acoloring thereon which contrasts with the color of the surrounding earthsoil, the improvement in which said sheet or tape is in the form of athin base member carrying a thin film of a metal on its oppositesurfaces, and a thin film protective coating over said metal which ismoistureand soil-resistant.

6. In a method for the installation of a line beneath the surface of theearth in which the line is placed within an excavation and subsequentlybackfilled and wherein there is included in the backfill at a generallypredetermined level adjacent the line an indicating means comprising atearable or rupturable flexible sheet or tape bearing a coloring thereonwhich contrasts with the color of the surrounding earth soil, theimprovement in which said sheet or tape is in the form of a thin basemember of a synthetic plastic material which is moistureandsoil-resistant, said base member carrying a metal on its surface, saidmetal being covered with a thin film protective coating which ismoistureand soil-resistant.

7. A method according to claim 5, wherein an elongated trench is firstexcavated, the line is placed longitudinally along and within saidtrench, the trench is partially backfilled, the tearable or rupturablesheet or tape is placed in said trench and overlying said line, and thencompleting the backfilling operation.

8. A method according to claim 1, in which the thin film protectivecoating is polyethylene.

9. A method according to claim 8, in which said polyethylene is colored.

10. A method according to claim 1, in which the thin film protectivecoating is a polyvinylidene chloride.

11. In an area of earth soil which carries beneath the surface thereofat least one element of construction and a frangible colored bodybeneath said surface and located above and overlying said element ofconstruction, said frangible body having a coloring thereon whichcontrasts with the color of the surrounding earth soil, the improvementin which said frangible colored body comprises a flexible sheet or tapein the form of a thin base member carrying a thin film of a metal on itsopposite surfaces, and a thin film protective coating over said metalwhich is moistureand soil-resistant.

12. An earth soil area according to claim 11, wherein the base member isa synthetic plastic.

13. An earth soil area according to claim 11, wherein the base member isan adhesive.

14. In a backfilled trench in the earth having an elongated lineadjacent the bottom thereof and, positioned intermediate said line andthe surface of the earth, and generally overlying said line, a flexibletearable or rupturable indicating sheet or tape bearing a coloringthereon which contrasts with the color of the surrounding earth soil,the improvement in which the said sheet or tape is in the form of a thinbase member of a synthetic plastic material which is moistureandsoil-resistant, said base member carrying a metal on its surface, saidmetal being covered with a thin film protective coating which ismoistureand soil-resistant.

15. A backfilled trench according to claim 14, in which the syntheticplastic material is polyethylene.

16. A backfilled trench according to claim 14, in which the syntheticplastic material is a colored polyvinylidene chloride.

1. In a method of facilitating the determination of the presence and thelocation of an element of construction disposed beneath the surface ofthe earth which includes the steps of digging a trench in the earth,providing an element of construction therein, placing a frangiblecolored body in said trench and overlying said element of constructionand in which said frangible body has a coloring thereon which contrastswith the color of the surrounding earth soil, the improvement in whichsaid frangible colored body comprises a flexible sheet or tape in theform of a thin base member carrying a thin film of a metal on itsopposite surfaces, and a thin film protective coating over said metalwhich is moisture- and soil-resistant.
 2. A method according to claim 1,wherein he base member is a synthetic plastic.
 3. A method according toclaim 1, wherein the base member is an adhesive.
 4. In a method offacilitating the determination of the presence and the location of anelement of construction disposed beneath the surface of the earth whichincludes the steps of digging a trench in the earth, providing anelement of construction therein, placing a frangible colored body insaid trench and overlying said element of construction and in which saidfrangible body has a coloring thereon which contrasts with the color ofthe surrounding earth soil, the improvement in which said frangiblecolored body comprises a flexible sheet or tape in the form of a thinbase member of a synthetic plastic material which is moisture- andsoil-resistant, said base member carrying a metal on its surface, saidmetal being covered with a thin film protective coating which ismoisture- and soil-resistant.
 5. In am method for the installation of aline beneath the surface of the earth in which the line is placed withinan excavation and subsequently backfilled and wherein there is includedin the backfill at a generally predetermined level adjacent the line anindicating means comprising a tearable or rupturable flexible sheet ortape bearing a coloring thereon which contrasts with the color of thesurrounding earth soil, the improvement in which said sheet or tape isin the form Of a thin base member carrying a thin film of a metal on itsopposite surfaces, and a thin film protective coating over said metalwhich is moisture- and soil-resistant.
 6. In a method for theinstallation of a line beneath the surface of the earth in which theline is placed within an excavation and subsequently backfilled andwherein there is included in the backfill at a generally predeterminedlevel adjacent the line an indicating means comprising a tearable orrupturable flexible sheet or tape bearing a coloring thereon whichcontrasts with the color of the surrounding earth soil, the improvementin which said sheet or tape is in the form of a thin base member of asynthetic plastic material which is moisture-and soil-resistant, saidbase member carrying a metal on its surface, said metal being coveredwith a thin film protective coating which is moisture- andsoil-resistant.
 7. A method according to claim 5, wherein an elongatedtrench is first excavated, the line is placed longitudinally along andwithin said trench, the trench is partially backfilled, the tearable orrupturable sheet or tape is placed in said trench and overlying saidline, and then completing the backfilling operation.
 8. A methodaccording to claim 1, in which the thin film protective coating ispolyethylene.
 9. A method according to claim 8, in which saidpolyethylene is colored.
 10. A method according to claim 1, in which thethin film protective coating is a polyvinylidene chloride.
 11. In anarea of earth soil which carries beneath the surface thereof at leastone element of construction and a frangible colored body beneath saidsurface and located above and overlying said element of construction,said frangible body having a coloring thereon which contrasts with thecolor of the surrounding earth soil, the improvement in which saidfrangible colored body comprises a flexible sheet or tape in the form ofa thin base member carrying a thin film of a metal on its oppositesurfaces, and a thin film protective coating over said metal which ismoisture- and soil-resistant.
 12. An earth soil area according to claim11, wherein the base member is a synthetic plastic.
 13. An earth soilarea according to claim 11, wherein the base member is an adhesive. 14.In a backfilled trench in the earth having an elongated line adjacentthe bottom thereof and, positioned intermediate said line and thesurface of the earth, and generally overlying said line, a flexibletearable or rupturable indicating sheet or tape bearing a coloringthereon which contrasts with the color of the surrounding earth soil,the improvement in which the said sheet or tape is in the form of a thinbase member of a synthetic plastic material which is moisture- andsoil-resistant, said base member carrying a metal on its surface, saidmetal being covered with a thin film protective coating which ismoisture- and soil-resistant.
 15. A backfilled trench according to claim14, in which the synthetic plastic material is polyethylene.
 16. Abackfilled trench according to claim 14, in which the synthetic plasticmaterial is a colored polyvinylidene chloride.